The proliferation and differentiation of somatic cells are regulated by multiple controls, in many systems by exogenous growth factors. The hematopoietic system is under the control of several well-defined growth factors, including erythropoietin. Erythropoietin (epo), a glycoprotein produced primarily by the kidney and also by renal neoplasms, is the primary regulator of red blood cell production in man and other vertebrates. Other growth factors have been defined in other systems, particularly transforming growth factors (TGF) which are hormone-like polypeptides that can reversibly induce the transformed phenotype - i.e. the ability to grow in soft agar, and the loss of anchorage dependence and of contact inhibition of growth. We have developed two cell lines derived from human renal neoplasms: a renal cell carcinoma line which produces epo and TGFAlpha and an adult Wilm's tumor line which produces epo and an unidentified TGF. The objective of the studies described in this proposal is therefore two-fold. The regulation of erythropoietin synthesis and secretion at the cellular level will be studied in our tumor lines and in normal kidney cells in vitro. Our radioimmunoassay, which is specific for erythropoietin, is sensitive enough to detect factor produced by these cells. We will study the synthesis and secretion of erythropoietin under basal, stimulated and suppressed conditions. Effectors such as oxygen, cobalt, calcium cAMP, prostaglandins and adrenergic agonists will be tested for their effects on secretion and synthesis of erythropoietin and on production of pre-erythropoietin mRNA. The transforming growth factor produced by the Wilm's tumor line has not as yet been defined. Therefore, we will attempt to purify and characterize this factor with respect to chemical structure, biological activity, and relationships to other growth factors. We will study alterations in cellular DNA and the presence of oncogenes in the two tumor cell lines. It is expected that information from these studies can aid our understanding of regulation of the synthesis and secretion of growth factors. It is possible that erythropoietin and the Wilm's transforming growth factor can serve as a circulating tumor marker for the presence of renal neoplasms in vivo.